Thermal stability of 5 nm barrier InAlN/GaN HEMTs

In this paper, the properties of 5 nm barrier HEMT devices has been investigated in a temperature ramping experiment as used for AlGaN/GaN devices. The pinch-off voltage remains identical and the Schottky diode leakage only marginally increased. The ohmic contacts, which have been alloyed at 850 degC by RTA show also exceptional stability. The initial alloying cycle still kept the alloy front just out of reach for high tunnelling probability. It has been moved within this distance in a very controlled way, however without degrading the contact resistance by the 1000 degC post alloying cycle. In conclusion, the InAlN/GaN heterojunction is exceptionally stable even for barrier thicknesses below 10 nm. Experiments for barrier thicknesses of approx. 2.5 nm (verified by a pinch-off voltage of -0.8 V) are presently performed and results will be reported.